1. Field of the Invention
The present invention relates to the field of gears. It concerns, more particularly, an improvement made to the teeth of gear wheels, particularly for the purpose of using them in precision mechanisms, such as those used in horology.
2. Description of Related Art
Clock and watch designers employ gears having a clearance or play, i.e. a difference in thickness, between the teeth of the wheels of the two gear wheels that cooperate with each other. This enables any dimensional defects in the wheels to be corrected.
Unfortunately, the presence of clearances in the gears also constitutes a drawback, because of the addition of plays, when, particularly in a watch, the second or the minute is displayed off-center. The hand is then very likely to “float” on the fixed marks on the dial. Such a defect is particularly disadvantageous for “top of the range” products.
Various solutions have been proposed to compensate for the gear defects.
For example, FR Patent No. 2 379 736 proposes that the teeth of one of the wheels are provided with a radial slot made at the tip thereof and that said slot opens into a recess, which enables them to be deformed elastically at the moment that they come into contact with the opposite teeth of the other wheel. Such a solution suffers, however, from the fact that the teeth are liable to become too fragile and/or to have insufficient rigidity to transmit, with a satisfactory yield, significant energy provided by a high couple. Moreover, this document is completely silent as to the gear clearance.